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A305809
Dirichlet convolution of A003415 (Arithmetic derivative) with itself.
11
0, 0, 0, 1, 0, 2, 0, 8, 1, 2, 0, 18, 0, 2, 2, 40, 0, 22, 0, 22, 2, 2, 0, 96, 1, 2, 12, 26, 0, 40, 0, 160, 2, 2, 2, 147, 0, 2, 2, 128, 0, 48, 0, 34, 28, 2, 0, 400, 1, 34, 2, 38, 0, 156, 2, 160, 2, 2, 0, 276, 0, 2, 32, 560, 2, 64, 0, 46, 2, 56, 0, 680, 0, 2, 36, 50, 2, 72, 0, 560, 90, 2, 0, 348, 2, 2, 2, 224, 0, 346, 2, 58, 2, 2, 2, 1440, 0, 46, 40, 267, 0, 88
OFFSET
1,6
LINKS
FORMULA
a(n) = Sum_{d|n} A003415(n/d)*A003415(d).
PROG
(PARI)
A003415(n) = {my(fac); if(n<1, 0, fac=factor(n); sum(i=1, matsize(fac)[1], n*fac[i, 2]/fac[i, 1]))}; \\ From A003415
A305809(n) = sumdiv(n, d, A003415(n/d)*A003415(d));
CROSSREFS
Cf. A008578 (positions of 0's), A001248 (of 1's), A006881 (of 2's).
Sequence in context: A239275 A186745 A109573 * A349139 A159810 A199268
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 13 2018
STATUS
approved